Corteks proposes to develop a micro-processor controlled self-optimizing amplifier specifically designed to record evoked potentials under adverse conditions. The device will have very high common-mode noise rejection, and markedly reduced susceptibility to stimulus artifact compared to current commercial devices. It is anticipated that these features will make this amplifier better suited for recording evoked potentials in electrically noisy environments, and for performing evoked potential studies which are currently difficult or impossible because of stimulus artifact. In Phase I, n prototype of the amplifier front-end, employing a novel circuit topology, was designed, constructed and tested. The device appears to be largely immune from the effects of stimulus artifact. In Phase II, digital signal processing will be incorporated at a critical point in the circuit to further improve amplifier performance, and automated montage selection techniques will be developed. Portions of the system will be converted to application specific integrated circuits to further improve performance and reduce cost. A prototype of a complete multichannel amplifier, including user interface, will be constructed and tested.